Sulfonates are a class of chemicals used in household, industrial, and institutional cleaning applications, personal care and agricultural products, metalworking fluids, industrial processes, emulsifying agents, corrosion inhibitors and as additives in lubricating oils. Some of the desirable properties of sulfonates for use in lubricating oil applications include their low cost, compatibility, water tolerance, corrosion inhibition, emulsion performance, friction properties, high temperature stability, rust performance, and light color.
Sulfonates that are used in lubricating oil applications have been classified as either neutral sulfonates, low overbased (LOB) sulfonates, or high overbased (HOB) sulfonates.
High overbased polyalkenyl sulfonates having a TBN up to 400 are known and can be prepared by conventional overbasing processes. However, super overbased polyalkenyl sulfonates having a TBN greater than 400 that have acceptable viscosities are not known and a process for their preparation is also not known. There are many well known processes for preparing high overbased polyalkenyl sulfonates and high overbased alkylaryl sulfonates. A number of patents and patent applications have disclosed methods for preparing high overbased polyalkenyl sulfonates and high overbased alkylaryl sulfonates.
U.S. Pat. No. 4,086,170 discloses overbased calcium sulfonates and concentrated oily solutions thereof are prepared by reacting a solution of alkylbenzene sulfonic acid with an excess of a calcium oxide having a medium or low activity towards water and with carbon dioxide. Oily solutions of overbased calcium sulfonate obtained from such a calcium oxide are perfectly limpid and are easily filterable.
U.S. Pat. No. 4,137,184 discloses metal sulfonates of the formula R—SO3M wherein R is a hydrocarbyl and m is a Group I or Group II metal or lead are overbased with Group II metal carbonate, bicarbonate, oxide or hydroxide. Also provided are lubricating oil compositions or concentrates containing these overbased sulfonates.
U.S. Pat. No. 4,880,550 discloses a method for preparing a carbonate overbased calcium sulfonate, which method comprises the steps of: (1) forming an initial mixture of a lower molecular weight alkanol, an alkyl or alkaryl substituted sulfonic acid or sulfonate compound, a diluent and a solvent; (2) adding a basic calcium compound to the initial mixture to form a second mixture in which the amount of added calcium is at least about ten times the amount necessary to form a neutral calcium sulfonate; (3) heating the second mixture to reflux temperature; (4) carbonating the second mixture at said reflux temperature to form a carbonated product which simultaneously and continuously removing water produced by the carbonation reaction; (5) after carbonation is stopped, heating the carbonated product to an elevated temperature sufficient to remove the alkanol; and (6) removing solids and solvent from the carbonated product.
U.S. Pat. No. 5,132,033 discloses lubricating oil containing an overbased oil-soluble composition prepared by adding water to a heated reaction mixture containing an alkaline earth metal halide, an alkaline earth metal salt of an alkaryl sulfonate, a hydrocarbon diluent-solvent, a lower alkanol, and an alkali metal oxide, and thereafter passing carbon dioxide through the reaction mixture.
U.S. Pat. No. 5,384,053 discloses a process for the production of a lubricating oil additive concentrate comprises reacting at elevated temperature component (A) a calcium hydrocarbyl-substituted sulfonate, component (B) an alkaline earth metal base added either in a single addition or in a plurality of additions at intermediate points during the reaction, component (C) at least one compound which is (i) a polyhydric alcohol having 2 to 4 carbon atoms, (ii) a di-(C3 or C4) glycol, (iii) a tri-(C2-C4) glycol, (iv) a mono- or polyalkylene glycol alkyl ether, component (D) a lubricating oil, component (E) carbon dioxide added subsequent to the, or each addition of component (B), component (F) a defined carboxylic acid or derivative, component (G) at least one compound which is (i) an inorganic halide or (an ammonium alkanoate or a mono-, tri- or tetra-alkyl ammonium formate or alkanoate provided that, when component (G) is (it), component (F) is not an acid chloride.
U.S. Pat. No. 6,054,419 discloses mixtures of alkylaryl sulfonates of superalkalinized alkaline earth metals comprising: (a) 50 to 85% by weight of a mono-alkyl phenyl sulfonate with a C14 to C40 linear chain wherein the molar proportion of phenyl sulfonates substituent is position 1 or 2 is between 0 and 13%, and (b) 15 to 50% by weight of a heavy alkylaryl sulfonate, wherein the aryl radical is phenyl or not, and the alkyl chains are either two linear alkyl chains with a total number of carbon atoms of 16 40, or one or a plurality of branched alkyl chains with on average a total number of carbon atoms of 15 to 48. In as much as these mixtures contain less than 10% of linear mono-alkyl phenyl sulfonate substituted in position 1 or 2 of the linear alkyl chain, they exhibit properties making them fit for use as detergents/dispersant additives for lubricating oils.
U.S. Pat. No. 6,159,912 discloses a low overbased alkyl phenyl sulfonate prepared by the neutralization of sulfonic acid with a sulfurized high TBN calcium alkylphenate in the absence of chloride and in the absence of additional carboxylic acid.
U.S. Pat. No. 6,204,226 discloses mixture of alkyl phenyl sulfonates of alkaline earth metals having: (a) from 20% to 70% by weight of a linear mono-alkyl phenyl sulfonate in which the linear mono-alkyl substituent contains from 14 to 40 carbon atoms, preferably from 20 to 24 carbon atoms, and the mole % of the phenyl sulfonate radical fixed on positions 1 or 2 of the linear alkyl chain is between 10% and 25%, preferably between 13% and 20%, and (b) from 30% to 80% by weight of a branched mono-alkyl phenyl sulfonate in which the branched mono-alkyl substituent contains from 14 to 18 carbon atoms.
U.S. Pat. No. 6,337,310 B1 discloses an alkylaryl composition wherein the aryl radical is other than phenol and wherein the alkyl radical is derived from an isomerized C14 to C40 normal alpha olefin wherein either (1) the weight percent of the aryl radical fixed at position 1 or 2 of a linear alkyl chain is less than about 23 or (2) at least 28 weight percent of the alkyl radicals are branched chain alkyl radicals, or (3) both, and is useful for making alkaline earth alkylaryl sulfonates that can be used as lubricating oil additives.
U.S. Pat. No. 6,410,491 discloses a polyalkylene sulfonic acid composition comprising a mixture of polyalkenyl sulfonic acids derived from a mixture of polyalkylenes comprising greater than 20 mole percent alkyl vinylidene and 1,1-di-alkyl isomers, and a method for making the composition. Also provided are low and high overbased sulfonates made from the mixture of polyalkenyl sulfonic acids, and lubricating oils containing the sulfonates.
U.S. Pat. No. 6,479,440 discloses an alkaline earth sulfonate having a BN of at least 250, wherein the aryl radical is not phenol, wherein the alkyl chain is a linear chain that contains between 14 and 40 carbon atoms, and wherein the mole % of the aryl-sulfonate radical fixed on positions 1 or 2 of the linear alkyl chain is between 13% and 30%. Such an alkaline earth alkylaryl sulfonate has improved compatibility, solubility and foaming performances while having low color and no skin formation. The starting alkylate has a low iodine number, a very high level of mono-alkylate, and as a consequence, a high yield at the sulfonation step.
U.S. patent application Ser. No. 10/714,469 (Publication No. US 2004/0102339 A1) discloses a method for improving the brake and clutch capacity of a functional fluid comprising adding a friction-modifying amount of a polyalkenyl sulfonate to the functional fluid, wherein the polyalkenyl sulfonate is an alkali metal or an alkaline earth metal salt of a polyalkylene sulfonic acid derived from a mixture of polyalkylenes comprising greater than about 20 mole percent alkyl vinylidene and 1,1-di-alkyl isomers.
U.S. patent application Ser. No. 10/660,948 (Publication No. US 2005/0059560 A1) discloses an improved process for making stabilized polyalkenyl sulfonic acids, whereby the product resulting from the reaction between a polyalkene and sulfur trioxide is stabilized by neutralizing with a neutralizing agent prior to storage or further processing. Neutralization at this point in the process results in polyalkenyl sulfonic acid that is stable and has decreased amount of sultones.
Super overbased polyalkenyl sulfonates are highly desirable for use in lubricating oils employable in diesel engines requiring a greater capability for neutralizing acidic matter, especially marine diesel engines. However, the conventional processes for the preparation of very highly overbased polyalkenyl sulfonates have problems associated with the very high, unacceptable viscosities of the products, which make them difficult to handle. Thus, there is a great need for a process for the preparation of overbased polyalkenyl sulfonates having a TBN greater than 400 and viscosities between 20 and 1,000 cSt at 100° C. Applicants have discovered a novel process for the preparation of polyalkenyl sulfonates having a TBN greater than 400, which process employs the addition of alkylaryl sulfonic acids or stabilized alkylaryl sulfonic acids to the polyalkylene sulfonic acids or the stabilized polyalkenyl sulfonic acids prior to the overbasing reaction.
It has surprisingly been found that the viscosity of the super overbased mixture of polyalkenyl sulfonates and alkylaryl sulfonates can be reduced 10 fold to 100 fold compared to the corresponding super overbased 100 percent polyalkenyl sulfonates when the overbased polyalkenyl sulfonates are prepared as super overbased polyalkenyl sulfonate and alkylaryl sulfonate composition. The super overbased alkylaryl sulfonate and polyalkenyl sulfonate composition is suitable for use in lubricating oil compositions requiring a high alkalinity reserve.